ADSORBENTS FOR CD REMOVAL FROM WATER WASTE: A SHORT REVIEW OF THE RECENT DEVELOPMENT - Management of Hazardous Residues Containing Cd - page 33

Agaricus bisporus and Calocybe indica were 34.96, 29.67 and 24.09 mg g -1 ,
respectively.
Bone char was used for Cd 2+ adsorption by Choy and McKay [136].
According to experimental data, the surface diffusion coefficient was
dependent on the initial metallic ion concentration. They made experiments
with aqueous solution of metallic ion solution concentrations of 2.1 and 5.4
mmol dm -3 and they found out that the surface diffusivities were 3.0x10 -9 to
8.8x10 -9 cm 2 s -1 , respectively. The maximum adsorption capacity of Cd 2+ was
53.62 mg g -1 at pH 4.9.
A comparison between several biosorbents for the removal of Cd 2+ is
summarized in Table 3.

C ONCLUSION

Miscellaneous low-cost source of agro-industrial wastes and biomaterials
have been utilized as effective adsorbents for cadmium removal from
wastewater. Several factors, e.g., pH, temperature, ionic strength, contact time,
adsorbent dose and initial concentration affect the adsorption process. In
general, the modification of materials has been successfully applied in some
cases to improve the adsorption capacity and removal efficiency. Additionally,
much more research is needed in this research field.

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